Best sprint HIIT sprint/rest (recovery) ratio

Hi guys, does anyone with experience with sprint HIIT workouts (with real, running sprinting as the actual sprint) know of the best sprint/recovery ratio? I hear about all these different types-- theres 8 seconds of sprinting/12 seconds of walking for something like 20 minutes (which I think is ridiculous), 30 seconds of sprinting/30 seconds of walking for eight intervals, but I have been doing 15 seconds of sprinting followed by 45 seconds of walking for ten intervals for the past couple months. This works great and has helped me lose a little bit of weight but there is ten pounds clinging on for dear life and it is really beginning to piss me off. So can anyone tell me what they think is the best ratio? By the way, please dont say something like 60 seconds of sprinting, I dont know why all of you think anyone can sprint for that long, and also Im talking about sprinting in terms of actual running as fast as you can and not like swimming or bicycling for as fast as you can. Thanks!
I also want to edit this to say that I do my 15 seconds of sprinting/45 seconds of walking ten times 3 times a week, and full body muscle building 3 days a week as well, both one day after the other, for 6 days a week. Since I am only doing sprinting for the actual fat loss, do you think that is why I am not getting results? I only workout hard for ten minutes a day. I know that sprints raise metabolism for hours after they are done, which results in fat loss, but is sprinting ALONE enough to get me into tip top shape? Thanks again

i usually do 30 secs sprinting with 45-60secs walking depending on my heart rate.I actually follow heart rate instead of time i.e. i sprint until i reach 175bpm and then start walking until it goes down to 150.then i start sprinting again etc etc...

[QUOTE=schnitzer31;834993451]i usually do 30 secs sprinting with 45-60secs walking depending on my heart rate.I actually follow heart rate instead of time i.e. i sprint until i reach 175bpm and then start walking until it goes down to 150.then i start sprinting again etc etc...[/QUOTE]
Oh thats very interesting... how do you know your heart rate though? Do you wear a piece of technology or something? Also do you think that the reason why I am not losing enough fat is specifically because my sprint/recovery ratio is too easy?

You can do it based on heart rate with a heart rate monitor. So you do your sprint, then wait until you recover to your recovery heart rate and sprint again. This is a great way to train, because your rest is determined by your fitness and how quickly you can recover. You can use the Karvonen formula to figure out what your recovery heart rate and max target heart rates are. Google it and do some research if you're going to use this method.

If you don't feel like bothering with the heart rate method and figuring out your exact numbers, the easier way is to just ramp up your recovery times. So you warm up, then do your first sprint of 15 seconds (for example). Your first rest interval would be around 10 seconds because it's your first sprint and you're still fresh (take more time if you do need it, depending on your fitness level). Then you sprint 15s again and you'll probably need 15s rest. Then 15s sprint again, 30s rest. Eventually you'll get to a point where you don't need to add more time after each sprint. This is 45s for some people, 60s for others and possibly even more than that. You'll just have to see. The basis of all this is that your recovery needs increase to a certain maximum recovery time with each sprint repetition you do. HIIT workouts should be very challenging, so don't cheat yourself. But get the rest you need to do all your sprints at 80-90% effort.

[QUOTE=ktj4l;835109731]You can do it based on heart rate with a heart rate monitor. So you do your sprint, then wait until you recover to your recovery heart rate and sprint again. This is a great way to train, because your rest is determined by your fitness and how quickly you can recover. You can use the Karvonen formula to figure out what your recovery heart rate and max target heart rates are. Google it and do some research if you're going to use this method.

If you don't feel like bothering with the heart rate method and figuring out your exact numbers, the easier way is to just ramp up your recovery times. So you warm up, then do your first sprint of 15 seconds (for example). Your first rest interval would be around 10 seconds because it's your first sprint and you're still fresh (take more time if you do need it, depending on your fitness level). Then you sprint 15s again and you'll probably need 15s rest. Then 15s sprint again, 30s rest. Eventually you'll get to a point where you don't need to add more time after each sprint. This is 45s for some people, 60s for others and possibly even more than that. You'll just have to see. The basis of all this is that your recovery needs increase to a certain maximum recovery time with each sprint repetition you do. HIIT workouts should be very challenging, so don't cheat yourself. But get the rest you need to do all your sprints at 80-90% effort.[/QUOTE]
Oo very informative, thanks, but do you think (it just occured to me) that maybe I cant lose this last ten pounds because I am relying solely on sprint hiit intervals as fat loss? Like, maybe I should do other things, like some kind of jump rope exercises or something, because sprints last like ten minutes and thats it and its only every other day for me... ugh, its just so confusing

[QUOTE=BetThisOnesFree;835192991]Oo very informative, thanks, but do you think (it just occured to me) that maybe I cant lose this last ten pounds because I am relying solely on sprint hiit intervals as fat loss? Like, maybe I should do other things, like some kind of jump rope exercises or something, because sprints last like ten minutes and thats it and its only every other day for me... ugh, its just so confusing[/QUOTE]It could also be your diet? If you aren't losing weight and you're on a cut, I would look to decreasing the amount of calories you eat per day. You can find details on how to accomplish this in the Nutrition forum (read the stickies there at the very least if you have not).

To tweak your cardio: All out sprints for 15s might not be optimal for fat loss. You could try doing them with a little less intensity, but longer. I.e. try 45s "sprints" (these are not all out, just as fast as you can go for 45s) for a few weeks instead (rest times increase as well obviously). I assume your HIIT is 5mins warmup, 15mins of actual work and 5mins cooldown, right? That's a good format. Jump roping is another alternative, but sprints are fine. Swimming or aqua jogging can be used for HIIT as well. You can even do it with weights depending on your lifting program.

There are many options, you can even switch it up. If you're lifting hard in the gym, I wouldn't do more than two HIIT sessions per week though. Any additional cardio should be low intensity in my opinion.